Java使用FTP上传文件并模拟接受的方法

0. 导入相关依赖

<!-- FTP -->
<dependency>
   <groupId>commons-net</groupId>
   <artifactId>commons-net</artifactId>
   <version>3.6</version>
 </dependency>
 <!-- Hutool:一个小而全的Java工具类库，具体介绍参照附录1 -->
 <dependency>
   <groupId>cn.hutool</groupId>
   <artifactId>hutool-all</artifactId>
   <version>5.3.7</version>
 </dependency>
 <!-- lombok:通过简单的注解的形式来帮助我们简化消除一些必须有但显得很臃肿的 Java 代码的工具,需要为idea添加插件，添加方法参照附录2 -->
 <dependency>
   <groupId>org.projectlombok</groupId>
   <artifactId>lombok</artifactId>
   <version>1.18.16</version>    
 </dependency>

1. 文件上传代码

@Component
@Slf4j
public class FTPTools {

  /**
   * 文件上传
   * @param hostname 域名地址
   * @param port 端口号
   * @param username 用户名
   * @param password 密码
   * @param fileInfo 待上传的文件
   * @param uploadPath 待上传到的路径
   * @param saveName 预保存的文件名
   * @return
   */
  public static boolean upload(String hostname,int port,String username,String password,String fileInfo,String uploadPath,String saveName){
    boolean flag = false;

    FTPClient ftpClient = null;
    try {
      ftpClient = new FTPClient();
      ftpClient.connect(hostname,port);
      //每次数据连接之前，ftp client告诉ftp server开通一个端口来传输数据
      ftpClient.enterLocalPassiveMode();
      //设置二进制传输
      ftpClient.setFileType(FTPClient.BINARY_FILE_TYPE);
      ftpClient.setControlEncoding("UTF-8");
      if(ftpClient.login(username,password)){//若连接成功
        log.info("成功登录到ftp服务端，开始文件上传");
        flag = sendFile(ftpClient,fileInfo,uploadPath,saveName);
      }else{
        log.error("登录到ftp服务端失败，请检查用户名和密码");
      }
      disconnect(ftpClient);
    }catch (SocketException e) {
      log.error("文件{}上传失败：{}",saveName,e.getMessage());
    } catch (IOException e) {
      log.error("文件{}上传失败：{}",saveName,e.getMessage());
    } finally {

    }
    return flag;
  }

  /**
   * 文件传输
   * @param fileInfo
   * @param uploadPath
   * @param saveName
   * @return
   */
  private static boolean sendFile(FTPClient ftpClient, String fileInfo, String uploadPath, String saveName) throws FileNotFoundException,IOException{
    boolean flag = false;
    try(FileInputStream fileInputStream = new FileInputStream(fileInfo)){
      //检查工作目录是否存在
      if(ftpClient.changeWorkingDirectory(uploadPath)){
      	if(ftpClient.listFiles(saveName).length != 0){ //检查文件是否已经存在
          boolean deleteFlag = ftpClient.deleteFile(saveName);
          log.info(deleteFlag?"文件已存在，直接删除":"存在同名文件且无法删除，请检查权限");
        }
        flag = ftpClient.storeFile(saveName,fileInputStream);
        log.info(flag?"文件上传成功！":"文件上传失败！");
      }else{
        log.error("找不到要上传的目录");
      }
    }catch (FileNotFoundException e){
      log.error("找不到要上传的文件{}：{}",fileInfo,e.getMessage());
      throw e;
    }catch (IOException e){
      log.error("文件传输异常：{}",e.getMessage());
      throw e;
    }
    return flag;
  }

  /**
   * 断开ftp连接
   * @param ftpClient
   */
  private static void disconnect(FTPClient ftpClient) {
    if (ftpClient.isConnected()){
      try{
        ftpClient.disconnect();
        log.info("ftp连接已关闭，文件上传结束");
      }catch (IOException e){
        log.error("ftp连接关闭失败:{}",e);
      }
    }
  }

}

2. FTP模拟测试环境搭建

通过IntelliJ IDEA lombok插件的安装和使用